Compression Ignition (CI) is the formal name for diesel engine operation. The history of compression ignition technology has generally lead to higher and higher injection pressure in within the fuel injector in order to enhance the mixing of diesel fuel and air in the cylinder. Prior to 1980 nearly all injector systems operated at pressure below about 2,000 psi. Today's systems can operate at pressures above 20,000 psi. These high pressure place severe demands on the fuel delivery system, but higher pressures allow for more fuel to be injected per unit time. As a result the injector may be opened and closed more than once during each compression cycle.
The high pressure thereby allows for some degree of shaping of the injected fuel by modulating the opening and closing sequence of the injector near top dead center (TDC) of the compression cycle.
Diesel fuel cannot be injected too far from top dead center because thorough mixing of fuel and air prior to achieving maximum pressure leads to preignition and detonation waves in the cylinder. Detonation is an undesirable reaction as shock waves are strong enough to damage the rings and piston crown. Therefore, the direct injection of diesel fuel must occur within a small number of crank angle degrees around TDC. At high speed this means that the time for fuel injection, droplet penetration, droplet evaporation, mixing with air, and finally deflagration type combustion must all occur in about one to two milliseconds.
Complete combustion is a challenge in this brief period and any process that can enhance any one of the aforementioned processes has merit for diesel technology. Herein, we detail a mechanism for increasing the reaction rate of the deflagration wave by means of a catalyst. The catalysts are electrostatically charged water droplets.